private void btThongKe_Click(object sender, RoutedEventArgs e)
{
ThongKe tk = new ThongKe(conn);
}
private void barQuanLyThongKeBanHang_ItemClick(object sender, ItemClickEventArgs e)
{
ThongKe frmThongKe = new ThongKe();
frmThongKe.ShowDialog();
}
